Topology discovery by active probing

Bradley Huffaker

Daniel Plummer

David Moore

kc claffy

CAIDA, San Diego Supercomputer Center, University of California San Diego

As the Internet has grown, so has the challenge of accurate
measurement and modeling of its topology. Commonly used but coarse
methods of measuring topology, e.g., BGP tables, suffer from several limitations.
To pursue more accurate empirically-based topology modeling.
CAIDA began its Macroscopic Topology Project in 1998, The project focus
is actively measuring topology and round trip time (RTT) information
across a wide cross-section of the commodity Internet. In this paper
we describe CAIDA's topology measurement architecture and our analysis
and visualization tools. We describe differences between IP and AS (BGP-based)
granularities of topology modeling, including advantages and limitations
of both, as well as how correlation between both types of data can yield
more relevant insights. We introduce four new visualization metaphors for
handling macroscopic topology data, as well as a tool for aggregating multiple
IP addresses into the same physical router. We highlight results of
our analyses, in particular relationships between RTT and topology data,
and how source and destination selection and geopolitical boundaries affect
those relationships.